Catheter mapping of retrograde atrial activation. Observations during ventricular pacing and AV nodal re-entrant paroxysmal tachycardia.

A systematic study of retrograde atrial sequence at commonly used electrode catheter recording sites in 8 patients without, and in 4 patients with AV nodal re-entrant paroxysmal tachycardia was made. During right ventricular pacing, the retrograde atrial activation sequence was low septal right atrium--proximal coronary sinus--distal coronary sinus--high right atrium. During the episodes of paroxysmal tachycardia, a similar pattern was observed. This information should be helpful in the understanding of abnormal activation sequences in patients with paroxysmal supraventricular tachycardia in whom retrogradely conducting anomalous pathways are suspected.